Recently, an anti-reflecting coating (ARC) film is widely employed in a field of manufacturing semiconductor devices in order to prevent, e.g., a generation of standing waves due to multiple interferences within a resist film during an exposure process using, e.g., a stepper. Conventionally employed as such an ARC film is an organic ARC film using an organic polymer.
FIGS. 8A to 8C describe an exemplary manufacturing process of a semiconductor device employing the organic ARC film.
As shown in FIG. 8A, formed on a semiconductor wafer (a silicon substrate) 201 are an insulating layer 202 made of, e.g., a silicon oxide film and a conductor layer 203 formed of, e.g., polysilicon and, further, formed on the conductor layer 203 by, e.g., a spin coating method are an organic ARC film 204 and a mask layer 205 made of a photoresist.
The mask layer 205 made of the photoresist is shaped into a predetermined pattern, as shown in FIG. 8B, by being exposed to light and being subsequently developed while undergoing an exposure process by, e.g., a stepper and a developing process by a developer system, respectively. Thereafter, the organic ARC film 204 is patterned to have a preset pattern, as shown in FIG. 8C, by being etched through the mask layer 205 by plasma etching employing an etching gas containing Cl2 and O2 gases.
Subsequently, the conductor layer 203 is etched through the mask layer 205 and the organic ARC film 204 into a predetermined pattern (not shown) and then the mask layer 205 and the organic ARC film 204 are removed by ashing.
As described above, the plasma etching employing the etching gas containing Cl2 and O2 gases has been conventionally employed to etch the organic ARC film.
In such a conventional method, however, it is difficult to form the organic ARC film 204 to have a vertical sidewall since a sidewall 204a of the organic ARC film 204 is of a tapered profile as shown in FIG. 8C.
Further, as illustrated in FIG. 9, if a shape of the pattern has a dense pattern region (a left part of the drawing) in which neighboring patterns are close to each other and a sparse pattern region (a right part of the drawing) in which neighboring patterns are spaced apart from each other, the sidewall profile tends to vary between the dense pattern region and the sparse pattern region.
That is, in the example provided in FIG. 9, a profile of the sidewall is found to be tapered more in the sparse pattern region than in the dense pattern region.
Further, such tapered profile of the sidewall tends to vary at a central portion and a peripheral portion even on a single wafer.
For this reason, it has been difficult to perform an etching such that sidewall profiles are formed to be consistently of a high quality throughout the central portion, the peripheral portion, the dense pattern region and the sparse pattern region of the semiconductor wafer, even in case of controlling the sidewall profiles by adjusting etching conditions such as a flow rate and a pressure of the etching gas, a temperature of the semiconductor wafer during the etching, a high frequency power supplied to an electrode of a parallel plate type plasma etching apparatus, and so on.